The double-spin-polarization observable E for γ p → pπ0 has been measured with the CEBAF Large Acceptance Spectrometer (CLAS) at photon beam energies Eγ from 0.367 to 2.173 GeV (corresponding to center-ofmass energies from 1.240 to 2.200 GeV) for pion center-ofmass angles, cos θc.m. π0 , between − 0.86 and 0.82. These new CLAS measurements cover a broader energy range and have smaller uncertainties compared to previous CBELSA data and provide an important independent check on systematics. These measurements are compared to predictions as well as new global fits from The George Washington University, Mainz, and Bonn-Gatchina groups. Their inclusion in multipole analyses will allow us to refine our understanding of the single-pion production contribution to the Gerasimov-Drell- Hearn sum rule and improve the determination of resonance properties, which will be presented in a future publication.
Measurement of the helicity asymmetry E for the γ→ p→ → pπ reaction in the resonance region: The CLAS Collaboration
Barion L.;Ciullo G.;Contalbrigo M.;Pappalardo L. L.;Vallarino S.;
2023
Abstract
The double-spin-polarization observable E for γ p → pπ0 has been measured with the CEBAF Large Acceptance Spectrometer (CLAS) at photon beam energies Eγ from 0.367 to 2.173 GeV (corresponding to center-ofmass energies from 1.240 to 2.200 GeV) for pion center-ofmass angles, cos θc.m. π0 , between − 0.86 and 0.82. These new CLAS measurements cover a broader energy range and have smaller uncertainties compared to previous CBELSA data and provide an important independent check on systematics. These measurements are compared to predictions as well as new global fits from The George Washington University, Mainz, and Bonn-Gatchina groups. Their inclusion in multipole analyses will allow us to refine our understanding of the single-pion production contribution to the Gerasimov-Drell- Hearn sum rule and improve the determination of resonance properties, which will be presented in a future publication.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
